feat(haproxy): filter dashboard tiles by agent haproxy capability

[sarg3nt]

Summary

• The HAProxy dashboard (/haproxy) attaches hx-get="/htmx/{box}/stats" + /metrics to every enabled server. On a box whose agent has no haproxy gear (e.g. container-mode agent on TrueNAS — issue Capability-driven autoconfig: every gear page must honor the active box's actual capabilities (umbrella) #112), those polls return 503 No stats available forever and the tiles stay empty. Light-hugger's deployment exhibits this whenever Mjolnir is in the box roster.
• Plumb the framework Handler.CapabilitiesCache through into the ServerAdapter and expose GetEnabledServersWithGearAvailable(gearName). The HAProxy gear's overview + status-grid handlers now filter through it, so boxes whose probe table marks haproxy as unavailable simply don't appear on the page.
• Fail-open: a box whose capabilities can't be fetched (agent unreachable, no API key, TLS verify off) is still included, matching how filterGearsByAgentCapabilities handles the same case. A transient agent outage doesn't make the page go dark.
• Default landing route per box (the other half of slice 3 in the roadmap) is left for a follow-up — this PR is scoped to the tile-filtering symptom.

Phase 2 slice of #112.

Test plan

• go build ./... clean
• go vet ./... clean
• go test -count=1 ./internal/framework/services/... ./internal/framework/handler/... ./internal/framework/agent/... ./internal/gears/haproxy/... clean
• On a deployment with a mixed box roster (one HAProxy host + one non-HAProxy agent), confirm the non-HAProxy box no longer appears on /haproxy and the 503 burst on /htmx/{nonHAProxy}/stats is gone.
• Confirm the page still renders for an agent that's temporarily unreachable (TLS verify off / agent down) — fail-open keeps the box visible.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates the HAProxy dashboard to avoid rendering (and continuously polling) HAProxy tiles for boxes whose agents report that the haproxy gear is unavailable, using the dashboard’s existing agent capability probe-table cache as the source of truth.

Changes:

• Plumbs the handler’s shared CapabilitiesCache into ServerAdapter and adds GetEnabledServersWithGearAvailable(gearName) for capability-aware box filtering.
• Updates HAProxy overview + status-grid handlers to use the new adapter method to filter out non-HAProxy-capable boxes (fail-open when capabilities can’t be fetched).
• Exposes Handler.CapabilitiesCache() and wires it in cmd/server/main.go during app startup.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
gearbox/internal/gears/haproxy/handlers.go	Filters HAProxy pages to boxes whose agents report haproxy available.
gearbox/internal/framework/services/server_adapter.go	Adds optional capabilities cache + filtering method for enabled servers by agent gear availability.
gearbox/internal/framework/handler/handler.go	Exposes the handler’s shared capabilities cache via an accessor.
gearbox/cmd/server/main.go	Wires the handler capabilities cache into the server adapter for use by gear plugins.

Comments suppressed due to low confidence (1)

gearbox/internal/gears/haproxy/handlers.go:36

• OverviewPage now bases the “no servers configured” redirect on the filtered HAProxy-capable list. If boxes are configured but none advertises the haproxy capability, this will redirect to /settings/boxes (which is misleading) and makes it impossible to show a “no HAProxy-capable boxes” empty state. Consider distinguishing between (a) zero enabled boxes vs (b) zero HAProxy-capable boxes, and render an explicit empty-state for (b) (or redirect to a more relevant settings page).

	servers := h.getHAProxyServers()

	// If no servers configured, redirect to servers settings page
	if len(servers) == 0 {
		http.Redirect(w, r, "/settings/boxes", http.StatusSeeOther)
		return

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.